In building and shaping wax in the field of denture work, the following steps are usually repeated more than ten times for one tooth; (a) first to heat up a spatula and to soften or melt solid wax and to scoop it by means of the heated spatula; (b) then to heat it up again to make it in a liquid form; and (c) to build it up at a region where wax shaping is to be performed.
In this conventional procedure, the point of regard of a dental technician moves outside of the region whenever the above steps are repeated. Accordingly, it is difficult for the dental technician to concentrate his attention on a wax shaping work, and consequently an efficiency of the work is extremely low.
In order to improve the efficiency of this troublesome work, there has been proposed a construction combining a heater and a spatula and providing direct heating of the spatula by the heater. Examples of such construction can be seen in U.S. Pat. No. 1,905,987, U.S. Pat. No. 2,097,098, U.S. Pat. No. 2,119,908, U.S. Pat. No. 2,468,818, U.S. Pat. No. 3,800,122, U.S. Pat. No. 3,902,043 and U.S. Pat. No. 4,301,357.
However, even if the spatula having the proposed construction is employed, the work includes essentially a step for dipping wax from another place and still requires the dental technician to make his point of regard move outside of the region where wax shaping is to be performed. Accordingly, the improvement in the efficiency of the work is not yet satisfactory.
Moreover, in another example, a construction of the conventional tool is disclosed in U.S. Pat. No. 2,243,400 wherein a heater and a wax reservoir are provided in a handle portion and wax melted by the heater is delivered to a spatula formed at a tip portion. However, since the molten wax is prestored in wax reservoir, as to the above example the construction has a drawback that there might occur a degradation of wax or a separation of wax component before the molten wax is delivered to the spatula and as a result the wax might become inadequate for the denture work in which a high tolerance is required.
The present inventors have proposed a tool disclosed in U.S. Pat. No. 4,770,633 in order to eliminate the drawback. The above-mentioned tool is generally constructed to slip down a wax cartridge by the self gravity. However, the subsequent study has proved that the construction is not necessarily satisfactory with respect to the operation.
For example, there is a problem that the wax cartridge falls out of the tool when the rear end of the tool is tilted downward in the course of slipping by self gravity of the wax cartridge for any reason.
An object of the present invention is to provide a wax shaping tool which can completely control a forward and backward movement of the wax cartridge, and therefore, which can freely adjust the amount and speed of wax melting speed thereof and can operate more properly than the conventional one.
Another object of the present invention is to provide a wax shaping tool which allow a dental technician to continuously perform a wax shaping work many times without making his point of regard move outside of the region to be shaped, and therefore, which enables a wax building and shaping work to be carried out rapidly and efficiently.
A further object of the present invention is to provide a wax shaping tool wherein solid wax is melted just before a wax building work so that the work can be carried out with avoiding the degradation of wax or the separation of wax component.
A further object of the present invention is to provide a wax shaping tool wherein a solid wax cartridge, which is apt to be softened and deformed by an external force, can be fed without deformation, bending or the like.